DataOutputpublic interface DataOutput The DataOutput interface provides
for converting data from any of the Java
primitive types to a series of bytes and
writing these bytes to a binary stream.
There is also a facility for converting
a String into
modified UTF-8
format and writing the resulting series
of bytes.
For all the methods in this interface that
write bytes, it is generally true that if
a byte cannot be written for any reason,
an IOException is thrown. |
| Methods Summary |
|---|
| public void | write(int b)Writes to the output stream the eight
low-order bits of the argument b.
The 24 high-order bits of b
are ignored.
| | public void | write(byte[] b)Writes to the output stream all the bytes in array b.
If b is null,
a NullPointerException is thrown.
If b.length is zero, then
no bytes are written. Otherwise, the byte
b[0] is written first, then
b[1], and so on; the last byte
written is b[b.length-1].
| | public void | write(byte[] b, int off, int len)Writes len bytes from array
b, in order, to
the output stream. If b
is null, a NullPointerException
is thrown. If off is negative,
or len is negative, or off+len
is greater than the length of the array
b, then an IndexOutOfBoundsException
is thrown. If len is zero,
then no bytes are written. Otherwise, the
byte b[off] is written first,
then b[off+1], and so on; the
last byte written is b[off+len-1].
| | public void | writeBoolean(boolean v)Writes a boolean value to this output stream.
If the argument v
is true, the value (byte)1
is written; if v is false,
the value (byte)0 is written.
The byte written by this method may
be read by the readBoolean
method of interface DataInput,
which will then return a boolean
equal to v.
| | public void | writeByte(int v)Writes to the output stream the eight low-
order bits of the argument v.
The 24 high-order bits of v
are ignored. (This means that writeByte
does exactly the same thing as write
for an integer argument.) The byte written
by this method may be read by the readByte
method of interface DataInput,
which will then return a byte
equal to (byte)v.
| | public void | writeBytes(java.lang.String s)Writes a string to the output stream.
For every character in the string
s, taken in order, one byte
is written to the output stream. If
s is null, a NullPointerException
is thrown. If s.length
is zero, then no bytes are written. Otherwise,
the character s[0] is written
first, then s[1], and so on;
the last character written is s[s.length-1].
For each character, one byte is written,
the low-order byte, in exactly the manner
of the writeByte method . The
high-order eight bits of each character
in the string are ignored.
| | public void | writeChar(int v)Writes a char value, which
is comprised of two bytes, to the
output stream.
The byte values to be written, in the order
shown, are:
(byte)(0xff & (v >> 8))
(byte)(0xff & v)
The bytes written by this method may be
read by the readChar method
of interface DataInput , which
will then return a char equal
to (char)v.
| | public void | writeChars(java.lang.String s)Writes every character in the string s,
to the output stream, in order,
two bytes per character. If s
is null, a NullPointerException
is thrown. If s.length
is zero, then no characters are written.
Otherwise, the character s[0]
is written first, then s[1],
and so on; the last character written is
s[s.length-1]. For each character,
two bytes are actually written, high-order
byte first, in exactly the manner of the
writeChar method.
| | public void | writeDouble(double v)Writes a double value,
which is comprised of eight bytes, to the output stream.
It does this as if it first converts this
double value to a long
in exactly the manner of the Double.doubleToLongBits
method and then writes the long
value in exactly the manner of the writeLong
method. The bytes written by this method
may be read by the readDouble
method of interface DataInput,
which will then return a double
equal to v.
| | public void | writeFloat(float v)Writes a float value,
which is comprised of four bytes, to the output stream.
It does this as if it first converts this
float value to an int
in exactly the manner of the Float.floatToIntBits
method and then writes the int
value in exactly the manner of the writeInt
method. The bytes written by this method
may be read by the readFloat
method of interface DataInput,
which will then return a float
equal to v.
| | public void | writeInt(int v)Writes an int value, which is
comprised of four bytes, to the output stream.
The byte values to be written, in the order
shown, are:
(byte)(0xff & (v >> 24))
(byte)(0xff & (v >> 16))
(byte)(0xff & (v >> 8))
(byte)(0xff & v)
The bytes written by this method may be read
by the readInt method of interface
DataInput , which will then
return an int equal to v.
| | public void | writeLong(long v)Writes a long value, which is
comprised of eight bytes, to the output stream.
The byte values to be written, in the order
shown, are:
(byte)(0xff & (v >> 56))
(byte)(0xff & (v >> 48))
(byte)(0xff & (v >> 40))
(byte)(0xff & (v >> 32))
(byte)(0xff & (v >> 24))
(byte)(0xff & (v >> 16))
(byte)(0xff & (v >> 8))
(byte)(0xff & v)
The bytes written by this method may be
read by the readLong method
of interface DataInput , which
will then return a long equal
to v.
| | public void | writeShort(int v)Writes two bytes to the output
stream to represent the value of the argument.
The byte values to be written, in the order
shown, are:
(byte)(0xff & (v >> 8))
(byte)(0xff & v)
The bytes written by this method may be
read by the readShort method
of interface DataInput , which
will then return a short equal
to (short)v.
| | public void | writeUTF(java.lang.String s)Writes two bytes of length information
to the output stream, followed
by the
modified UTF-8
representation
of every character in the string s.
If s is null,
a NullPointerException is thrown.
Each character in the string s
is converted to a group of one, two, or
three bytes, depending on the value of the
character.
If a character c
is in the range \u0001 through
\u007f, it is represented
by one byte:
(byte)c
If a character c is \u0000
or is in the range \u0080
through \u07ff, then it is
represented by two bytes, to be written
in the order shown:
(byte)(0xc0 | (0x1f & (c >> 6)))
(byte)(0x80 | (0x3f & c))
If a character
c is in the range \u0800
through uffff, then it is
represented by three bytes, to be written
in the order shown:
(byte)(0xe0 | (0x0f & (c >> 12)))
(byte)(0x80 | (0x3f & (c >> 6)))
(byte)(0x80 | (0x3f & c))
First,
the total number of bytes needed to represent
all the characters of s is
calculated. If this number is larger than
65535, then a UTFDataFormatException
is thrown. Otherwise, this length is written
to the output stream in exactly the manner
of the writeShort method;
after this, the one-, two-, or three-byte
representation of each character in the
string s is written. The
bytes written by this method may be read
by the readUTF method of interface
DataInput , which will then
return a String equal to s.
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